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  <title>This function encrypts data</title>

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</div><hr /><div id="function.mcrypt-generic" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">mcrypt_generic</h1>
  <p class="verinfo">(PHP 4 &gt;= 4.0.2, PHP 5)</p><p class="refpurpose"><span class="refname">mcrypt_generic</span> &mdash; <span class="dc-title">This function encrypts data</span></p>

 </div>
 
 <div class="refsect1 description" id="refsect1-function.mcrypt-generic-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="type">string</span> <span class="methodname"><strong>mcrypt_generic</strong></span>
    ( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$td</code></span>
   , <span class="methodparam"><span class="type">string</span> <code class="parameter">$data</code></span>
   )</div>

  <p class="para rdfs-comment">
   This function encrypts data. The data is padded with &quot;<em>\0</em>&quot;
   to make sure the length of the data is n * blocksize. This
   function returns the encrypted data. Note that the length
   of the returned string can in fact be longer than the input,
   due to the padding of the data.
  </p>
  <p class="para">
   If you want to store the encrypted data in a database make sure to store
   the entire string as returned by mcrypt_generic, or the string will not
   entirely decrypt properly.  If your original string is 10 characters long
   and the block size is 8 (use
   <span class="function"><a href="function.mcrypt-enc-get-block-size.html" class="function">mcrypt_enc_get_block_size()</a></span> to determine the
   blocksize), you would need at least 16 characters in your database field.
   Note the string returned by <span class="function"><a href="function.mdecrypt-generic.html" class="function">mdecrypt_generic()</a></span> will be
   16 characters as well...use rtrim($str, &quot;\0&quot;) to remove the padding.
  </p>
  <p class="para">
   If you are for example storing the data in a MySQL database remember that
   varchar fields automatically have trailing spaces removed during
   insertion. As encrypted data can end in a space (ASCII 32), the data will
   be damaged by this removal.  Store data in a tinyblob/tinytext (or
   larger) field instead.
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.mcrypt-generic-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">td</code></em></dt>

     <dd>

      <p class="para">
       The encryption descriptor.
      </p>
      <p class="para">
       The encryption handle should always be initialized with
       <span class="function"><a href="function.mcrypt-generic-init.html" class="function">mcrypt_generic_init()</a></span> with a key and an IV before
       calling this function. Where the encryption is done, you should free the
       encryption buffers by calling <span class="function"><a href="function.mcrypt-generic-deinit.html" class="function">mcrypt_generic_deinit()</a></span>.
       See <span class="function"><a href="function.mcrypt-module-open.html" class="function">mcrypt_module_open()</a></span> for an example.
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">data</code></em></dt>

     <dd>

      <p class="para">
       The data to encrypt.
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.mcrypt-generic-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   Returns the encrypted data.
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.mcrypt-generic-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.mdecrypt-generic.html" class="function" rel="rdfs-seeAlso">mdecrypt_generic()</a> - Decrypts data</span></li>
    <li class="member"><span class="function"><a href="function.mcrypt-generic-init.html" class="function" rel="rdfs-seeAlso">mcrypt_generic_init()</a> - This function initializes all buffers needed for encryption</span></li>
    <li class="member"><span class="function"><a href="function.mcrypt-generic-deinit.html" class="function" rel="rdfs-seeAlso">mcrypt_generic_deinit()</a> - This function deinitializes an encryption module</span></li>
   </ul>
  </p>
 </div>


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